A: 

One solution just occurred to me, but I still need to iron out the bugs:

Since the session start is stored in the cookie, I can have a function that, prior to any ajax request, checks to see if the cookie is set to expire. If it is, I can just reload the page they are on, using the same URL, and that will hit the session-expired page.

Anthony  2009-07-13 21:01:46
On the other hand, I am still left wondering if there IS in fact a way to push the entire page toward the redirect in the moment that the server returns it, rather than having to use a redirect URL (which isn't an option.)
Anthony  2009-07-14 03:07:59

related questions

How do I write Firefox add-on that automatically enters proxy passwords?
Login Integration in PHP
Strange Rails Authentication Issue
Concurrent logins in a web farm
Is there a browser equivalent to IE's ClearAuthenticationCache?
How can I authenticate using client credentials in WCF just once?
Why can't I connect to my CAS server with Perl's AuthCAS?
Best Solution For Authentication in Ruby on Rails
Authenticate on an ASP.Net Forms Authorization website from a console app
How do I use NTLM authentication with Active Directory
What have you used Windows CardSpace for, if anything
Forms Authentication across Applications
Retreiving the PC Name of a Client? (Windows Auth)
How would you implement FORM based authentication without a backing database?
What's the best way to authenticate over WCF?
Only accepting certain ajax requests from authenticated users
OpenID authentication in Ruby on Rails
OpenID Attribute Exchange - should I use it?
OpenID: which provider should I recommend to my users?
What to use for login ID?
ASP.NET authentication: user name Vs User ID
How do I add SSL to a .net application that uses httplistener - it will *not* be running on IIS
How can I get the authenticated user name under Apache using plain HTTP authentication and PHP?
Checklist for IIS 6/ASP.NET Windows Authentication?
The Definitive Guide To Website Authentication